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What's inside of these modern electronic ballasts for florescent shop
lights and other straight tube fixtures? I know these ballasts are
being sold more and more to replace the old iron core magnetic types,
but what's going on inside of them? Obviously there are semiconductors
and other electronic components. I would suspect that a capacitor
discharges to start the bulbs.

I tried to google a schematic, found several showing how to wire them
(same as the old style ballasts), but none show the innards or a
schematic that explains how they work.

I also wonder how durable and reliable they are compared to the old
ones? Electronics are often more likely to burn out from power line
surges caused by lightning and load surges. Since surges occur in all
electrical systems, are the electronic types as durable as the old coil
wrapped around iron ("transformer") types.

wrote:
What's inside of these modern electronic ballasts for florescent shop
lights and other straight tube fixtures? I know these ballasts are
being sold more and more to replace the old iron core magnetic types,
but what's going on inside of them? Obviously there are semiconductors
and other electronic components. I would suspect that a capacitor
discharges to start the bulbs.

I tried to google a schematic, found several showing how to wire them
(same as the old style ballasts), but none show the innards or a
schematic that explains how they work.

I also wonder how durable and reliable they are compared to the old
ones? Electronics are often more likely to burn out from power line
surges caused by lightning and load surges. Since surges occur in all
electrical systems, are the electronic types as durable as the old coil
wrapped around iron ("transformer") types.

Thanks

You got bridge to make dc, mosfets to switch at high frequency, inductor
and caps.
More efficient but probably less reliable, but ballasts break too.

On Sunday, May 6, 2012 3:47:02 PM UTC-5, (unknown) wrote:
What's inside of these modern electronic ballasts for florescent shop
lights and other straight tube fixtures? I know these ballasts are
being sold more and more to replace the old iron core magnetic types,
but what's going on inside of them? Obviously there are semiconductors
and other electronic components. I would suspect that a capacitor
discharges to start the bulbs.

I tried to google a schematic, found several showing how to wire them
(same as the old style ballasts), but none show the innards or a
schematic that explains how they work.

I also wonder how durable and reliable they are compared to the old
ones? Electronics are often more likely to burn out from power line
surges caused by lightning and load surges. Since surges occur in all
electrical systems, are the electronic types as durable as the old coil
wrapped around iron ("transformer") types.

Thanks

From the ones I have installed...they are at least as reliable. The 4 ft-4 tube ones are 125-270volt. So they must clamp the voltage. The lasts ones I received were even smaller now. Although as long, maybe slightly bigger than an inch square.

wrote in message
...
What's inside of these modern electronic ballasts for florescent shop
lights and other straight tube fixtures? I know these ballasts are
being sold more and more to replace the old iron core magnetic types,
but what's going on inside of them? Obviously there are semiconductors
and other electronic components. I would suspect that a capacitor
discharges to start the bulbs.

I tried to google a schematic, found several showing how to wire them
(same as the old style ballasts), but none show the innards or a
schematic that explains how they work.

I also wonder how durable and reliable they are compared to the old
ones? Electronics are often more likely to burn out from power line
surges caused by lightning and load surges. Since surges occur in all
electrical systems, are the electronic types as durable as the old coil
wrapped around iron ("transformer") types.

The surge protection feature has been included since the 1980s when the
first electronic ballasts were used in buildings. Whole buildings were
converted, lightning struck and whole buildings went dark with ballast
failures. One manufacturer went bankrupt trying to honor warranty
replacements. Doesn't take too many of those to get the attention of the
industry.

No, the new electronic ballasts don't appear to be as durable as the old
"core-and-coil" types -- not much to go wrong with a wire wrapped around a
few steel plates; but just like a TV or any other electronic device, the
circuitry is reliable depending upon the manufacturer. A bonus is that
lamps are more efficient and last longer on electronic ballasts. I built a
house 10 years ago with indirect fluorescent lighting in most of the rooms.
There are 20+ ballasts. So far, one lamp has failed -- no ballast failures.
And, last year set a new record for rain and lightning storms in the area.

Just like any other electronic device, I think heat and capacitor wear out
are or will be the cause of most electronic ballast failures. CFL bulbs are
good examples of that.

Nothing like good old planned obsolescence. How much would it really
cost the manufacturers to substitute electrolytic caps with somewhat
higher power ratings? I'd gladly pay an additional $0.20 - $0.50 per
CFL or fixture for substantially longer mean time before failure.

the caps in there are 105degF 250V caps,seem to be rated fine.
electrolytics DO have a finite lifetime,usually several thousand hours of
operation. But the CFLs often are in "hot" environments that shorten their
lifetime. That's why many are not rated for "base up" operation;the ballast
receives the heat from the fixture.

switcher power supplies usually put a fast rise waveform across the
caps,that have high harmonics and generates a lot of internal heat.
electrolytics lasted a lot longer at 60Hz frequencies and sine-wave
operation.

On Mon, 07 May 2012 15:54:21 -0400, Tony Miklos
wrote:
Nothing like good old planned obsolescence. How much would it really
cost the manufacturers to substitute electrolytic caps with somewhat
higher power ratings? I'd gladly pay an additional $0.20 - $0.50 per CFL
or fixture for substantially longer mean time before failure.

As long as electronic ballasts are lasting (fairly long in my opinion)
I'd bet they are already using a high quality cap where it really
counts... on the high frequency circuits. Electrolytic caps often
suffer from ESR, and the only place this is normally a problem is the
high freq switching circuits and if they where using cheap caps there,
the life of a ballast may be only a year or two. I'm having much better
luck with el cheapo "lights of america" brand ones. No complaints here.

Is this bad capacitor thing "planned obsolescence"?
It must be. That's all I hear in the last decade. Computers, and other
electronics, ballasts, and the list goes on.......

Back in the 1960's and 70's I worked on electronics as a hobby and did
repairs. Much of the stuff was old vacuum tube stuff and early
transistor stuff. I *rarely* had to replace caps. It was normally a
tube, transistor, bad connection, or a bad potentiometer. When a cap
went bad, the device did nto stop working, just there would be hum in
the speaker from a weak filter cap. Much of the stuff I worked on was
20 or 30 years old. In fact I still have a 1940's tube type shortwave
radio and it still has the original caps and works well.

You'd think that with our technology that caps would be BETTER than they
used to be..... instead they're junk. If they want to keep putting
these foreign made junk caps in our electronics, maybe everyone should
stop buying the crap until they begin using good caps. I'm sure they
can make good ones......

You'd think that with our technology that caps would be BETTER than they
used to be..... instead they're junk. If they want to keep putting
these foreign made junk caps in our electronics, maybe everyone should
stop buying the crap until they begin using good caps. I'm sure they
can make good ones......